The invention relates to communications, and more particularly to communications with remote vehicles from a central location, and most particularly to communications with remote vehicles using earth satellites and cellular telephone systems.
Voice communications with remote vehicles, such as long haul trucks, from a control center is both inconvenient and inefficient. Presently, truckers must stop at a facility with a landline telephone to call their control, or dispatching, center to relay location information, to receive revised instructions, or the like. Finding such a facility that can accommodate a large, unwieldy vehicle is problematical, and the down time associated with stops wastes valuable time.
Non-voice data transmission by means of a satellite link is currently becoming available. In this system a central control facility is linked by landline telephone to a satellite link facility having a radio transmitter/receiver and an antenna, and the truck cab is provided with a computerized data terminal connected to a radio transmitter/receiver and a satellite antenna. Messages are :sent from the central control facility to the satellite link where they are sent by the radio transmitter to the satellite. The satellite retransmits the messages to the truck where they are received by the antenna and radio receiver and displayed on the data terminal. Messages from the truck are transmitted to the central control facility by the same system.
Voice communications are now commonly available by cellular telephone. In this system local telephone landlines are connected with mobile telephones by means of a multiplicity of transmitters and receivers each covering an area known as a "cell". As a vehicle with a mobile telephone moves from location to location, the connection is automatically switched to the cell best covering the current vehicle location. The group of contiguous cells under control of a common operator and operating under a single FCC license are referred to as "service areas". Normally calls from cell to cell within a service area are without additional charge. However, calls from service area to service area are subject to additional charges.
Long haul trucks could use standard cellular telephone services, but cellular telephones making calls from outside their "home" service area are subject to a special "roaming" surcharge, which are typically $2 to $3 per day, in addition to "long distance" toll charges. However, calls initiated within the service area are not subject to the surcharge. Unfortunately, in order to make calls from the control center, it is necessary to know the service area in which the vehicle is currently located. Also, in order to control the relatively high cost of roaming charges, it is desirable that only the dispatcher be able to initiate a phone call between the control center and the remote vehicle.
It is therefore an object of the present invention to provide more efficient and economical voice communications between a control center and a remote vehicle.
It is another object of the present invention to provide economical voice communications via a cellular telephone connection between a control center and a remote vehicle.
It is a further object of the present invention to permit remote vehicles to initiate a cellular telephone communication only with approval of the dispatching center.
It is yet another object of the present invention to combine non-voice satellite communications with voice cellular telephone communications to provide a more efficient and economical communications system.
Still other objects will become apparent in the following summary and description of a preferred embodiment of the invention.